Goliath frogs build nests for spawning – the reason for their gigantism?

ABSTRACT

In contrast to its popularity, astonishingly few facts have become known about the biology of the Goliath Frog, Conraua goliath. We herein report the so far unknown construction of nests as spawning sites by this species. On the Mpoula River, Littoral District, West Cameroon we identified 19 nests along a 400 m section. Nests could be classified into three types. Type 1 constitutes rock pools that were cleared by the frogs from detritus and leaf-litter; type 2 constitutes existing washouts at the riverbanks that were cleared from leaf-litter and/or expanded, and type 3 were depressions dug by the frogs into gravel riverbanks. The cleaning and digging activities of the frogs included removal of small to larger items, ranging from sand and leaves to larger stones. In all nest types eggs and tadpoles of C. goliath were detected. All nest types were used for egg deposition several times, and could comprise up to three distinct cohorts of tadpoles. Nests seemed to be clustered. Camera trapping revealed that nests are guarded by adult frogs at night. The breeding nests may allow the frogs to deposit their eggs away from the torrent rivers, and potential egg and tadpole predators. As nest construction, at least in some cases, requires the removal of large and heavy items, we hypothesize that this can only be achieved by decent sized frogs, possibly explaining the unique size of the species.

KEYWORDS:

• Amphibia
• Anura
• Cameroon
• Conraua goliath
• Conrauidae
• parental care

Supplemental data

Supplemental data for this article can be accessed here.

Acknowledgements

We thank the CamHerp CBF provided accommodation in their field station and logistic support. We thank the Penja district administration who granted access to the study site and the Cameroonian Ministry of Scientific Research and Innovation (MINRESI) for research permits (000062-65/MINRESI/B00/C00/C10/C12). Kristina von Rintelen (MfN) identified the shrimp. Two anonymous reviewers provided very helpful suggestions and questions!

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We thank the ‘Stiftung Artenschutz (Amphibian Funds)’ in cooperation with the ‘Verband der Zoologischen Gärten e.V. (VdZ)’ for funding, supported with additional supplies by ’Frogs & Friends e.V.’ and the ‘Tiergarten Schönbrunn’.